Surgical handpiece with self-sealing switch assembly

ABSTRACT

An bipolar electrosurgical tool ( 10 ) for cauterizing or ablating tissue. The tool has a nose cone ( 12 ) which serves as a handle. A conductive shaft ( 14 ) extends from the nose cone. A tip assembly ( 18 ) with an active electrode ( 20 ) is mounted to the shaft. A circuit board ( 78 ) is mounted in the nose cone. Conductive traces that forming contact pads ( 96, 102 ) are formed on the circuit board. A web ( 108 ) formed from a single piece of elastomeric material is seated over the opening in which the printed circuit board is mounted to seal the opening shut. Integrally formed with the web are buttons ( 116, 118 ) that are in registration over the contact pads. The buttons can be depressed downwardly towards the contact pads. When a button is so depressed, a conductive landing pad ( 120 ) integral with the button closes the connection between the traces that form the contact pad. Thus, the tool of this invention is provided with switches. The circuit board also has two conductive traces ( 92, 104   a ) that run in parallel. If there is a leak into the nose cone, a connection is established across these traces and shorts out a resistor ( 105 ). The shorting out of this resistor provides a control console ( 22 ) with an indication that there is a leak. The electrode is formed from a single piece of tantalum. The electrode has a head formed with a hole ( 172 ) trough which fluid flows. The electrode is seated in a sleeve ( 136   b ) provided with a through bore ( 177 ) in registration with the electrode hole.

RELATIONSHIP TO EARLIER FILED APPLICATION

This Application is a continuation-in-part of U.S. patent applicationSer. No. 09/310,067, filed May 11, 1999, now U.S. Pat. No. 6,214,003.The foregoing application, now a patent, is incorporated herein byreference.

FIELD OF THE INVENTION

This invention is related generally to a power-actuated surgical toolwith a handle-mounted self-sealing switch assembly. One particularversion of this tool is an electrosurgical tool that has handle-mountedswitches, is relatively easy to manufacture, provides an indication iffluid penetrates its handle and that has tip that fosters fluidcirculation adjacent the surgical site to which it is applied.

This invention is also related generally to a system and method ofshrinking capsulary tissue and, more particularly, to a system andmethod for shrinking capsulary tissue by applying heat, thermal energy,to the tissue.

BACKGROUND OF THE INVENTION

Electrosurgical tools have been used for a number of years to cut andshape tissue at the surgical sites to which these tools are applied. Atypical electrosurgical tool has an elongated shaft, sometimes called a“probe,” with a handle at one end and a tip at the opposed end. One typeof electrode surgical tool available to surgeons is referred to as abipolar electrosurgical tool. An active electrode is fitted into the tipof this tool. The shaft of the bipolar electrosurgical tool functions asthe return or reference electrode. The tool is applied to a surgicalsite at which there is a saline solution, a conductive fluid. A voltageis applied at a very high frequency, 50 k Hz to 10 M Hz, from the activeelectrode to the adjacent end of the shaft. This signal flows through,arcs through, the saline solution and the body tissue against which thetip is applied. When the signal is at a relatively low power, typicallyunder 40 Watts, the signal can coagulate fluid such as blood to seal thetissue closed. When the signal is at a relatively high power, typically20 Watts or more, it vaporizes the tissue to which it is applied so asto ablate, remove, the tissue. The overlap in the power ranges betweenthe coagulation and ablation modes of operation is due to the fact that,for a given power setting, whether or not a particular electrodecoagulates or ablates tissue is also a factor of the size and shape ofthe head of the electrode. Often, when an electrosurgical tool is usedto ablate tissue, it is considered to be operated in the “cutting” mode.

Many currently available electrosurgical tools are designed so thatmounted to the handles are switches for regulating the on/off state ofthe tool and the mode in which the tool is operated. The mounting ofthese switches to the tool handle makes it possible for the surgeon to,with a single hand, control both the position of the tool and theoperation of the tool. The switches are typically mounted to the toolhandle in liquid-tight seal assemblies. This mounting is necessary toprevent the conductive liquid that is often present in a surgicalenvironment from entering the handle and shorting out any electricalcomponents therein.

Presently available electrosurgical tools work reasonably well for thepurposes for which they are designed. However, there are still somelimitations associated with the currently available tools. Some of theselimitations are due to the fact that, when an electrosurgical tool isoperated in the ablation mode, bubbles form on the surface of the activeelectrode. One reason these bubbles form is that the electrical energydischarged by the electrode heats the conductive saline solution thatsurrounds the electrode. The heating of this solution causes it tovaporize and form bubbles. Initially, when relatively low levels of heatare present, the fluid immediately adjacent the surface of the electrodeis subjected to thin film boiling and transitional boiling. In this typeof vaporization, relatively small bubbles of gaseous state solutionform.

However, when additional thermal or electromagnetic energy is radiatedfrom the surface of the active electrode, the adjacent saline solutionis subjected to rapid nucleate boiling. During nucleate boiling,relatively large bubbles of vaporized solution form on the surface ofthe electrode. These bubbles are sometimes referred to as gas pockets.Moreover, during some high powered cutting modes of operation, theelectrical current applied to the solution and surrounding tissue causeselectrochemical processes to occur in this tissue and liquid. Theseelectrochemical processes produce gaseous state products that contributethe formation of large bubbles and the gas pockets.

At a minimum, these bubbles are a nuisance. The presence of thesebubbles interferes with the surgeon's view of the surgical site. This isespecially a problem when the electrosurgical tool is employed in anendoscopic surgical procedure. In an endoscopic procedure, theelectrosurgical tool is applied to the surgical site through a smallopening formed in the patient's body known as a portal. The surgeonviews the surgical site through an endoscope that is directed to thesurgical site through another portal. An advantage of an endoscopicsurgical procedure in comparison to a conventional surgical procedure isthat it requires less of the patient's body to be opened up in order togain access to the surgical site. However, when a conventionalelectrosurgical tool is employed in an endoscopic surgical procedure,the bubbles generated in the relatively small confines of the space ofthe surgical site can significantly block the surgeon's view of thesite.

Moreover, these bubbles are electrically and thermally insulating. Thelarge bubbles that form gas pockets during high powered cutting caninhibit the flow of new solution that rewets the electrode.Consequently, the bubbles reduce the extent to which current can arcthrough the tissue that is to be ablated. Sometimes, these bubblessignificantly reduce current flow through the tissue. The current flowstays in the reduced state until the bubbles collapse or move away andthe saline solution or body fluid flows back into the space between theelectrode and the shaft. Thus, sometimes when a presently availableelectrosurgical tool is actuated, the current only flows in a pulsepattern through the tissue to be ablated.

Moreover, many current electrosurgical tools are provided with wirewound electrodes. It is difficult to form wire wound electrodes so thatthey have heads with shapes that are especially useful for performingelectrosurgical procedures.

Providing a seal around the handle switches can significantly add to theoverall cost and assembly of the tool.

Also, sometimes, even with the best seals, there may be liquid leakageinto the handle of an electrosurgical tool. This leakage, if notpromptly detected, at a minimum, can lead to the degradation of the toolperformance. In a worse case scenario, this leakage can cause aconductive path to develop along the outer surface of the handle. Ifthis occurs, the personnel handling the tool may be subjected toelectrical shock.

Still another method by which an electrosurgical tool is employed toshape, remove very selected amounts of tissue is by a capsularyshrinkage procedure. In a capsulary shrinkage procedure, the cellsforming soft tissue are desiccated, reduced in size. In this type ofprocedure, as a result of the heating of the active electrode, there isa conductive transfer of the heat from the electrode to the location atwhich the capsulary shrinkage of tissue is to occur. The thermal energyapplied to the site causes the cells forming the tissue at the site toundergo capsulary shrinkage. This process is referred to as a thermallycapsulary shrinkage procedure.

In a presently available electrosurgical tool, internal to the tip ordistal end of the shaft there may be a small thermistor or othertemperature-sensitive transducer. This transducer monitors thetemperature of the active electrode to inferentially provide anindication of the temperature of the surgical site. This temperaturedata is very important because there is a limited temperature range towhich tissue can be heated in order to foster its shrinkage withoutcausing damage to the tissue. More particularly thermal capsularyshrinkage of tissue is best performed by heating the tissue to atemperature between 60 and 70° C. If the tissue is heated to atemperature above this range, it may suffer damage. More particularly,the cells forming the tissue may die if heated to a temperature above70° C. Therefore, when a thermal capsulary procedure is now performed,the temperature of the active electrode is monitored in order toregulate the application of an energization voltage to the electrode.Specifically, the application of the energization voltage to the activeelectrode is controlled to maintain its temperature within the range atwhich the thermal capsulary shrinkage process can best occur and toprevent it from rising to level at which cell death or damage can occur.

One disadvantage of the presently available electrosurgical tools isthat the transducer internal to the tool only measures the temperatureof the adjacent active electrode. This temperature measurement is onlyan approximate measurement of the temperature at the site to which theelectrode is applied. Given the presence of fluids and other materialaround the active electrode and, more particularly, between thetransducer and the surgical site, this measurement may not accuratelyrepresent the temperature at the site to which the electrode is applied.

Still another disadvantage associated with the currently availableelectrosurgical tool relates to the fact that often an AC signal is usedto energize the active electrode. This signal generates strayelectromagnetic waves. These electromagnetic waves interfere with thegeneration of the output signal generated by the transducer.Accordingly, it is now common practice to energize an electrosurgicaltool in an on/off/on/off pulsed pattern. During time periods when theenergization signal is pulsed on, the transducer signal is not employedas a feedback signal since it is adversely affected by the strayelectromagnetic waves. Only during the time periods at which theenergization signal is pulsed off, and the transducer signal isrelatively noise free, is the signal then employed by the downlinecomponents as the input signal for regulating the application of energyto the active electrode.

One disadvantage of this mechanism is that the pulsing of currentthrough the active electrode may stress the material from which theelectrode is formed. Another disadvantage of this process is that thepulsing causes the thermal energy generated by the electrode to itselfbe generated in an on/off/on/off pattern. The cyclic generation of thisheat can cause it to be unevenly applied to the surgical site. Theuneven application of this heat can in turn both make it difficult tocontrol the application of heat and lengthen the time it takes toperform the desired thermal capsulary shrinkage procedure.

SUMMARY OF THE INVENTION

This invention is related generally to a new and useful electrosurgicaltool. The tool of this invention has a tip assembly with an electrodethat facilitates the flow of conductive fluid to constantly rewet theactive electrode during low powered operation as well as the eduction oflarge bubbles/gas pockets away from electrode during higher poweredoperation. More specifically, the tip assembly is designed to fosterconvective fluid circulation around the surfaces of the electrode thatconstantly rewets those surfaces and transports the larger bubbles awayfrom the electrode. This circulation also serves to clean debris awayfrom the electrode. In order to foster this fluid flow, the electrodeand a complementary insulator of the tip assembly of this invention areformed with portals through which this fluid flows.

The tool of this invention also has a handle, a nose cone, in which thecircuitry internal to the tool is mounted on a printed circuit board. Aleak detect circuit is located on the periphery of the printed circuitboard. A complementary control console continually monitors the signalfrom this leak detect circuit. The switches integral with the nose coneinclude static components that are mounted on the printed circuit board.The switches have moving components that are integrally formed on a webthat is fitted to the nose cone. The web is designed to self-seal intoplace when mounted to the nose cone.

In some versions, the tool of this invention also has a fiber opticcable that is fitted in the tool shaft and that extends proximally awayfrom the tip. The fiber optic cable terminates at a transducer that issensitive to infra-red light. The transducer, based on the quantity ofthe received light, generates an electrical signal representative of thetemperature at the surgical site. The output signal generated by thetransducer is applied to the control unit that regulates the applicationof the output power signal to the tool electrodes. The control unit usesthe transducer output signal as a feedback signal for regulating themagnitude of the energization signal applied to the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is pointed out with particularity in the claims. Theabove and further features of this invention may be better understood byreference to the following description taken in conjunction with thefollowing drawings in which:

FIG. 1 is perspective view of an electrosurgical tool of this inventionand the control unit and foot switch assembly to which the tool isconnected;

FIG. 2 is an exploded view of the electrosurgical tool;

FIG. 3 is a perspective view of the hub;

FIG. 4 is a cross sectional view of the hub;

FIG. 5 is a perspective view of one of the connector pins that ismounted to the hub;

FIG. 6 is a perspective view of the nose cone of the electrosurgicaltool;

FIG. 7 is a cross sectional view of the nose cone;

FIG. 8 is a plan view of a printed circuit board that is mounted insidethe nose cone;

FIG. 9 is a schematic diagram of the electronic circuit integral withthe nose cone;

FIG. 10 is perspective view of the top of the web;

FIG. 11 is a cross sectional view of the web;

FIG. 12 is a cross sectional view of the proximal end of the shaft ofthe electrosurgical tool;

FIG. 12A is a cross sectional view of the proximal end of the shaft ofFIG. 12;

FIG. 13 is a cross sectional view depicting how the active electrode isheld in place and secured to the complementary wire to which theelectrode is connected;

FIG. 14 is a perspective view of a first preferred tip assembly of thisinvention;

FIG. 15 is an exploded view of the first tip assembly;

FIG. 16 is a cross sectional view of the first tip assembly;

FIG. 17A is a side view of the flow of bubbles away from the first tipassembly when the tool to which it is attached is operated in thecutting mode; and

FIG. 17B is a side view of the flow of bubbles away from the first tipassembly after the tool to which it is attached has been in operationand the tissue to which the tip assembly is applied has flexed;

FIG. 18 is a perspective view of a second preferred tip assembly of thisinvention;

FIG. 19 is a partially exploded view of the second tip assembly in whichthe head of the electrode is upwardly directed;

FIG. 20 is a partially exploded view of the second tip assembly in whichthe head of the insulating sleeve is upwardly directed;

FIG. 21 is a cross sectional view of the second tip assembly;

FIG. 22 is a perspective view of a third preferred tip assembly of thisinvention;

FIG. 23 is a plan view of the electrode of third tip assembly;

FIG. 24 is a perspective view of the insulating sleeve of the third tipassembly;

FIG. 25 is a cross sectional view of the third tip assembly;

FIG. 26 is a perspective view of a fourth tip assembly of thisinvention;

FIG. 27 is an exploded view of the fourth tip assembly;

FIG. 28 front plan view of the fourth tip assembly;

FIG. 29 is a top plan view of the fourth tip assembly; and

FIG. 30 is a cross sectional view of the fourth tip assembly;

FIG. 31 is a block diagram depicting how the leak detect trace andcomplementary control console of the tool of this invention cooperate toprevent the actuation of the tool when a leak is detected in the handle;

FIG. 32 is a cross sectional view of the distal end of the shaft of anelectrosurgical tool illustrating how the tool is fitted with a fiberoptic cable; and

FIG. 33 is a schematic and block diagram of a control console depictinghow a signal representative of temperature at the surgical site isobtained and used to regulate the operation of the surgical tool.

DETAILED DESCRIPTION

FIGS. 1 and 2 depict the basic electrosurgical tool 10 of thisinvention. The tool 10 includes an elongated shell-like nose cone 12that serves as the handle for the tool. Extending forward from the frontend of the nose cone 12 is a shaft 14 formed from conductive metal. (Inthis application, “front”, “forward” and “distal” shall be understood tomean towards the surgical site to which the tool is applied. “Rear”,“rearwardly” and “proximal” shall be understood to mean away from thesurgical site.) Substantially all of the shaft 14, except for its distalend, is covered by an insulating tube 16.

A tip assembly 18 extends forward from the distal end of shaft 14. Anelectrode 20 is housed in the tip assembly 18. More precisely, electrode20 is considered an active electrode and the exposed distal end of shaft14 functions as a return or reference electrode. When theelectrosurgical tool 10 is actuated, current flows from electrode 20 tothe exposed end of shaft 14. The current either coagulates or ablatesthe tissue against which the tip assembly 18 is placed.

The current for energizing the electrosurgical tool comes from a controlconsole 22. Current flows from console 22 to the tool 10 through adetachable cable 21. The control console 22 converts the line voltageinto a high frequency signal suitable for applying across the toolelectrode 20 and the shaft 14. Depending on the surgeon's commands, thecontrol console 22 applies either a low power coagulation-causing signalto electrode 20 or a high powered, ablation-causing signal.

The actual power of the signal generated by the control console 22 isalso a function of the type of electrosurgical tool that is attached tothe console as will be discussed hereinafter. Also, the surgeon iscapable of setting the power to a specific level. For example, based onthe depression of either an up switch 23 or a down switch 24 on the faceof the console 22 the surgeon can, respectively, raise and lower thepower setting of the tool when the tool is operated in the cutting mode.A display 25 indicates the cutting mode power level at which theelectrosurgical is set to operate. By depressing a low power button 26,a medium power button 27 or a high power button 28 on the face of theconsole, the surgeon can control which one-of-three power levels thetool is operated at when it is operated in the coagulation mode.

The actual on/off actuation of the electrosurgical tool is controlled bytwo normally-open switches 29 and 30 mounted to the nose cone 12. Whenthe surgeon wants to operate the electrosurgical tool 10 in the cuttingmode, he/she depresses switch 29. When the surgeon wants to operate theelectrosurgical tool in the coagulation mode, he/she depresses switch30.

A surgeon may alternatively control the tool 10 with a foot switchassembly 32. Foot switch assembly 32 includes a set of depressible footswitches 33, 34, 35 and 36 that respectively, can be depressed toperform that same functions as are performed by up switch 23, downswitch 24, cutting-on switch 29 and coagulation-on switch 30.

The portion of the electrosurgical tool 10 to which the cable 21 isattached is a hub 42. The hub 42, which is the most rearwardlypositioned portion of the tool 10 is formed from a plastic such as PVCor ABS. The hub 42, now described in detail by reference to FIGS. 3 and4, is generally shaped to have a forward extending inner shell 44 thatis seated inside the open rear end of the nose cone 12. An outer shell46 is located around the exposed rear end of the inner shell 44. Smallribs 48 extend between the inner and outer shells 44 and 46,respectively, to provide stability to the outer shell. The outer shell46 is the exposed portion of the hub 42. The hub 42 has a solid,cylindrical core 50 that extends from the end of the hub forward axiallythrough the inner shell 44. Supports 52 that extend between the core 50and inner shell 44 hold the core in position.

Socket pins 54 seated in the core 50 receive pins integral with thecable 21, (cable pins not illustrated). Each socket pin 54 is seated ina separate through bore 56 that extends through the core 50 along anaxis that is parallel to the longitudinal axis of the bore. The core 50is formed so that the rear end of each bore 56 has an outwardlychamfered section 58. This shaping of the bores 56 facilitates theinsertion of the socket pins 54 into the bores. From FIG. 5 it can beseen that each socket pin 54 has first and second sections 60 and 62,respectively. Each first section 60 is generally sleeve shaped and isdesigned to receive a wire that is crimped in place. The pin firstsection 60 is the portion of the pin 54 seated in the bore 56. The pinsecond section 62 is sleeve like and further formed to have a slit 64that runs approximately the length of the section. The pin secondsection is the portion of the pin that extends rearwardly out of the hubcore 50. The second section 62 is the portion of the pin that receivesthe complementary pin integral with cable 21. One suitable socket pin 54is manufactured by AMP, Inc. of Harrisburg, Pa.

It will be further noted that, in the depicted version of the invention,a small post 66 is integrally formed with the core 50 and extendsrearwardly from the end of the core. Post 66 prevents the socket pins 54from being inadvertently bent.

The nose cone 12, now described by reference to FIGS. 6 and 7, is formedfrom a plastic such as PVC or ABS. The nose cone 12 has a generallyelongated shape. The front end of the nose cone 12 is shaped to have aninwardly directed taper. Shaft 14 and insulating tube 16 extend out ofthe front end of the nose cone 12. The front end of the nose cone 12 isgenerally solid. Nose cone 12 is further formed to have a void space 70that extends from approximately the longitudinal mid point of the nosecone to the open rear end of the nose cone. The hub inner shell 44 seatsextends into the open rear end of the nose cone 12 and seats in theadjacent portion of void space 70.

Nose cone 12 is further formed to have a bore 72 that extends rearwardlyfrom the front tip of the nose cone. Bore 72 extends rearwardly from thefront of the nose cone into void space 70. The bore 72 is the spacewithin the nose cone 12 in which the rear end of shaft 14 is seated. Inthe depicted version of the invention, nose cone 12 is formed so thatthe forward portion of bore 72 is actually a counterbore 74 that has adiameter that is slightly wider than that of the remaining, rearwardlyextending portion of the bore. Counterbore 74 is provided to provide aspace inside the nose cone for accommodating the rearward section of theinsulating tube 16 this fitted around shaft 14.

The nose cone 12 is further formed to have an opening in the top of thecone that serves as a wiring space 76. The wiring space 76 is the spaceinside the nose cone in which a printed circuit board 78 (FIG. 2) ismounted. The wiring space 76 extends from a point rearward and abovecounterbore 74 to a point over void space 70. A passageway 80 connectsthe wiring space 76 to void space 70. Wires 79 from the printed circuitboard 78 extend through passageway 80 so that they can be connected tothe socket pins 54 integral with hub 42. The nose cone is also shaped tohave a flange 82 that extends upwardly from the base of wiring space 76.The flange 82 is in the form of a closed-loop that is generallyrectangularly shaped and that has rounded corners. Flange 82 serves asthe member internal to nose cone 12 for supporting the printed circuitboard 78. There are two opposed posts 84 located immediately inside thefront and rear ends of the flange 82. Posts 84, which extend a slightdistance above the top edge of flange 82, serves as the structuralelements to which the printed wiring board 78 is snap fitted.

In the depicted version of the invention, nose cone 12 is also formed tohave a boss 86 that extends upwardly from the base of wiring space 76and that is located immediately rearward of the forward wall of flange82. Boss 86 is formed with a conduit 88 that extends from the top of theboss into bore 72. In some preferred methods of manufacturing theelectrosurgical tool 10 of this invention, shaft 14 and sleeve 16 arefitted in place within bore 72 and counterbore 74. Then, an adhesive isinjected into bore 72 and counterbore 76 through conduit 88. Thisadhesive at least partially fills bore 72 so as to secure the shaft 14and sleeve 16 in place.

The printed circuit board 78, shown in detail in FIG. 8, is formed fromany conventional substrate material from which printed circuit boardsare formed. The top surface of the printed circuit board 78 is formed tohave two conductive traces 92 and 94 that are arranged in one locationto form a contact pad 96 for switch 30. A branch of conductive trace 92,in combination with a third conductive trace 98, are arranged at asecond location on the printed circuit board to form a contact pad 102for switch 29.

Printed circuit board 78 also has a fourth conductive trace 104. Aresistor 105 extends between trace 92 and trace 104. Resistor 105 servesas an identification member that identifies the particular type ofelectrosurgical tool. In one preferred version of the invention, whenthe tool 10 is connected to the control console 22, resistor 105 becomespart of a voltage divider 220 (FIG. 31), the rest of which is internalto the control console. A voltage measuring circuit 222 internal to thecontrol console 22 measures the voltage across the resistor 22. Thisvoltage indicates to the control console 22 the power levels of thesignals that should be applied to the electrosurgical tool attached tothe console. The console 22, based on this indication, applies anenergization signal appropriate for the type of tool to the tool 10.

It will further be observed that conductive trace 104 is arranged on theprinted circuit board 78 so that a branch 104 a of the trace extendsaround the outer perimeter of the board. Conductive trace 104 a isarranged so that it is in close proximity to the portions of conductivetrace 92 that form contact pads 96 and 102. In particular, it will beobserved that conductive trace 92 defines at least 90° of the perimeterof each contact pad 96 and 102. Trace 104 a is parallel to the portionsof the trace 92 that define the perimeter of the contact pads. Moreparticularly trace 104 a is spaced a maximum of 30 mils (0.030 inches)and preferably 20 mils or less away from the portions of trace 92 thatdefine the perimeter of the contact pads 96 and 102. The purpose of thisarrangement will be explained hereinafter.

A web 108, seen in FIGS. 10 and 11, formed of elastomeric material suchas silicon rubber covers the nose cone wiring space 76 and printedcircuit board 78. The web 108 is shaped to have a generally flat basesection 110 that substantially covers the wiring space 76. A lip 112extends perpendicularly downwardly from the perimeter of base section110 and surrounds the base section. The lip 112 is formed to have a slit114 that is extends downwardly from a position located in the middle ofthe lip and that extends circumferentially around the web 108. The web108 is further formed so that ribs 115 extend the inner wall of the lip112.

Web 108 is dimensioned to be compression fitted into wiring space 76.Specifically, the lip 112 of web 108 is designed to tightly fit,compression secure, into the space between the outer wall of nose coneflange 82 and the walls internal to the nose cone 12 that define theouter perimeter of wiring space 76. When the web 108 is so fitted inplace, the web ribs 115 collapse inwardly. When the web is sopositioned, it also serves to hold the printed circuit board 78 inposition.

The web 108 is further shaped to have two flexible buttons 116 and 118that are integrally formed with base section 110. Button 116 is themoving component of switch 29 and is positioned over contact pad 102.Button 118 is the moving component of switch 30 and is positioned overcontact pad 96. Each button 116 and 118 is formed so that theundersurface thereof, the surface facing the printed circuit board 78,functions as a landing pad 120. Each landing pad 120 is formed fromgraphite or other material to make the landing pad conductive. In someversions of the invention, the conductive material is a copper disk orcopper paint that is applied to the underside of the button.

The depression of button 116 causes the associated landing pad 120 toabut and close the connection between conductive traces 92 and 98. Thedepression of button 118 causes the associated landing pad 120 to abutand close the connection between conductive traces 92 and 94.

As seen by FIG. 12, the shaft 14 is generally in the form of anelongated hollow tube. Typically, the shaft 14 is formed from stainlesssteel. Shaft 14 is further formed so as to have a small window 124 thatis located immediately forward of the proximal end of the shaft.

When the electrosurgical tool 10 of this invention is assembled, aninsulated wire 126 through which current is supplied to electrode 20 isfed into the center of shaft 14 through window 124. An insulated wire128 is employed to serve as the reference/return conductor from shaft14. An exposed end 130 of wire 128 is placed in the proximal end of theshaft 14. The proximal end of the shaft 14 is then crimped down over thewire so as to mechanically and electrically connect wire 128 to theshaft. Typically, this crimping is performed by an automated tool withfingers that simultaneously presses different arcuate sections of theshaft inward towards the wire and against each other.

As a result of this crimping, the crushed portions of the shaft 14 forman longitudinally extending slot 132, best seen in FIG. 12A. The portionof wire 126 that extends out of window 124 is seated in slot 132. Itwill further be observed that as a result of this crimping of theproximal end of shaft 14, the end of the shaft and as well as thesection of wire 126 seated in slot 132, subtend a space less than thediameter of the rest of the shaft, (diameter shown in phantom in FIG.12A). Thus, after this crimping operation, the crimped end of the shaft14 can still be fitted in nose cone bore 72.

FIG. 13 generically illustrates a tip 18 and electrode 20 of thisinvention, how these components are mounted in shaft 14 and how wire 126is connected to the electrode 20. The tip 18 includes an insulatingsleeve 136 formed from an appropriate material. In some versions of theinvention, sleeve 136 is formed from a ceramic such as yttriumtetragonally stabilized zirconium oxide. The sleeve 136 has an elongatedbase 138 that is seated in the open distal end of shaft 14. Sleeve 136is further formed to have a head 140, with a diameter equal to theoutside diameter of shaft 14, which is integral with base 138. Thesleeve head 140 abuts the open end of shaft 14. The exposed end of theelectrode 20 seats in the sleeve head 140.

The active electrode 20 is typically formed from tantalum. Typically,the electrode 20 is formed out of single piece of metal that is moldedinto shape by a progressive die-stamping process. In some preferredversions of the invention, the active electrode 20 is formed from asheet of metal having a thickness between 10 and 30 mils. In morepreferred versions of the invention, the initial workpiece from whichthe electrode is formed has a thickness of between 15 and 25 mils. Inthe progressive die-stamping process, the metal workpiece from which theelectrode 20 is formed is sequentially shaped in a set of dies until theelectrode has the desired final end shape.

The material from which the preferred active electrode is formed,tantalum, is economically obtainable in sheet metal form and the metalitself can readily be stamped or molded into shape. Thus, by forming theelectrode from tantalum, it is possible to provide electrodes havingnumerous different geometric shapes, some of which are disclosed below.Also, given ease with which it can be stamped or molded into shape, itis relatively economical to provide a specifically-shaped activeelectrode using the preferred material of this invention.

Electrode 20 is shaped to have an elongated stem 142. Stem 142 extendsrearwardly through a longitudinally oriented bore 144 formed in thesleeve 136. The electrode stem 142 actually extends a short distancebeyond the rear end of sleeve 136.

A crush tube 146 mechanically connects the exposed proximal end ofelectrode stem 142 to an exposed end 148 of wire 126. The crush tube 146is formed from a malleable conductive metal such as stainless steel.During the manufacture of the tool 10, the electrode stem 142 is coveredwith an adhesive 150 and fitted in sleeve bore 144. Crush tube 146 isplaced over the exposed end of the electrode stem 142 and the exposedend 148 of wire 126 is fitted in the distal open end of the crush tube.The crush tube 146 is then crimped down over the electrode stem 142 andwire end 148. In this last step, the exposed head end of the electrode20 may be pushed rearward. Thus, the crush tube 146 serves multiplefunctions. While the adhesive 150 that holds the electrode stem 142 insleeve bore 144 cures, the crush tube 146 serves as anchor to hold theelectrode 20 in place. Even after the adhesive cures, the crush tube 146holds the electrode 20 in the sleeve 136. Further, the crush tube 146secures the electrode 20 to the wire 126 over which the energizationcurrent is supplied to the electrode.

The detailed structure of one particular tip assembly 18 a that can beused with the electrosurgical tool 10 of this invention is now describedby reference to FIG. 14-16. Tip assembly 18 a includes an electrode 20 aseated in a complementary insulating sleeve 136 a. Electrode 20 a has ahead 155 that extends from the distal end of electrode stem 142. Theelectrode 20 a is shaped so that head 155 has the shape of asemi-spherical shell. Thus, the inner surface of the electrode is spacedaway from the adjacent surface of the insulating sleeve 136 a. It willbe noted that the distal end of the electrode stem 142, the portionconnected to the electrode head 155, is curved. More specifically, thedistal end of the stem 142 is shaped so that the rest of the stemprojects rearwardly along an axis that intersects both the center outersurface of the electrode head 155 and the center of the sphere inscribedby the head.

Electrode head 155 is formed to have three through windows 156. Windows156 project upwardly from the outer perimeter of the head 155 and extendthrough the head. The windows 156 are spaced equangularly around theelectrode head 20 a. It will further be noted that electrode 20 a isformed so that the windows 156 are defined by corners 163 that have a90° profile around the outer surface of the electrode. Windows 156subtend a significant amount of surface area on the outside of theelectrode head 155. For example, if the outer surface of the electrodehead subtends a radius of 67.5 mils, each window, which has a generallysemicircular profile, subtends a radius of 20 mils. As a result of theformation of windows 156, the electrode head 155 has three curved sidewalls 160. The portions of the perimeter of the electrode head 155between the windows 156 are referred to as the tines of the electrodehead.

Sleeve 136 a is formed with an open ended head 140 a shaped to receivethe head 155 of electrode 20 a. The head 140 a is formed to have aforward directed lip 164 that extends around the outer perimeter of thehead. Lip 164 defines the space in the front end of the sleeve head 140a in which the electrode head 155 is seated. The lip 164 is formed withthree equangularly spaced apart notches 165. When the electrode 20 a isseated in sleeve 136 a, the electrode windows 156 are in registrationwith the sleeve notches 165. Thus, the electrode windows 156 and sleevenotches 165 collectively form oval-shaped portals pathway that allowfluid to flow through the electrode head 155 from one side of the head155 to the other side. The purpose for allowing this fluid flow isdiscussed below.

Tip assembly 18 a of this invention is designed to foster the flow ofbubbles away from the surgical site to which the assembly is applied.FIG. 17A depicts the flow of bubbles 158 that occurs when the tipassembly 18 a is initially applied to tissue 169 at a surgical site andthe tool 10 is operated in the cutting mode. At this point in thesurgical procedure, the tissue 169 is not yet bent outwardly by theforce of the electrode head 155. At this point in the process, thefollowing activities occur that foster bubble flow away from thesurgical site. First, as a result of the current flow through electrode20 a, the electrode head 155 begins to heat up. The thermal energy inthe electrode head heats the surrounding solution. The heating of thissolution causes its expansion so that it becomes more buoyant than thesurrounding solution. This buoyant solution convects switch away fromthe surgical site. Consequently cooler, less buoyant solution flowstoward the surgical site as represented by arrow 158. Specifically, thereplacement solution flows towards the outer surface of the electrodehead since this is where some of this thermal expansion of solution isoccurring.

However, the outer surface of the electrode head 155 is not the onlylocation at which the heating causes the solution to convect away fromtip assembly 18b. The solution adjacent the inner surface of electrodehead 155 is also heated. This solution is similarly warmed to the pointat which it likewise convects away from the from tip assembly 18 a. Morespecifically, this solution convects away from the electrode head 155through the portals defined by electrode head windows 156 and sleevenotches 165. This convective flow is represented by arrow 161. Thisconvective flow away tip assembly 18 a causes a portion of thereplacement convective flow that is flowing towards the outer surface ofthe electrode head 155 to flow through the portals as represented byarrow 162. This fraction of the replacement flow replaces the heatedfluid that is convected away from the inner surface of the electrodehead 155. Thus the replacement solution flows towards the electrode head155 along flow paths that run both parallel to the axis of the toolshaft and transverse to this axis. In other words, as a result of theheating of the solution adjacent the electrode head 155, a convectivefluid flow pattern develops around the surgical site.

Eventually, sufficient thermal energy is supplied to the solutionadjacent the surgical site that the solution vaporizes. Thisvaporization is the cause of the initial formation of bubbles at thesurgical site. More particularly, this vaporization results in the rapidformation of bubbles 158 along both the inner and outer surfaces of theelectrode head 155. These bubbles do not simply remain clustered aroundthe electrode head 155. Instead, the convective flow away from theportals in the tip assembly educts the bubbles 158 in a stream that isdirected rearwardly away from the electrode head 155.

The previously described convective flow of liquid towards the surgicalsite continues simultaneously with this bubble formation. The constantreplenishment of this rewetting flow ensures that there is liquid-statefluid at the surgical site that is either thermally expanded, or beingforced away from the site due to the rapid formation of bubbles. Thisliquid-state fluid flow further promotes the general migration ofbubbles away from the surgical site.

As the surgical procedure continues, tip assembly 18 a forces theadjacent tissue 169 to flex so as to develop the concave profiledepicted in FIG. 17B. Eventually, bubbles 167 form adjacent the sidewalls 160 of the electrode head 155. It is believed these bubbles 167form as a result of the electrochemical reactions that take place due tothe generation of relatively strong electromagnetic fields adjacent theelectrode head 155. The concave bend of the adjacent tissue 169 directsthe already existing convective fluid flow away from the tip assembly 18b rearwardly. Thus, these bubbles 167 tend to be caught up in this fluidflow and move rearwardly away from the surgical site. Moreover, itshould be understood that bubbles 167 are able to move rearwardlybecause the portals through the tip assembly 18 a provide a flow pathfor the replacement liquid that is flowing towards the electrode head.As discussed above, and as represented by arrow 168, this fluid isdiverted laterally into the portals where it serves as replacement fluidfor the solution that has been convected away from the inner surface ofthe electrode head 155. Furthermore, the bubbles 167 themselves serve toblock the longitudinal flow of replacement fluid towards the outersurface of the electrode head 155. Since the portals provide a bleedflow path for this liquid-state fluid, this fluid does not function as amedium for transporting the bubbles forward towards the tissue 169 thatdefines the surgical site.

Furthermore, as previously discussed, the flow through some of theportals is bidirectional. This convective flow contributes to theeduction of the bubbles 167 away from the tip assembly 18 a.

It will further be observed in FIG. 17B that vaporization inducedbubbles 158 continue to be formed. These bubbles 158 become entrained inthe flow of the bubbles produced adjacent the head side walls 160.

Thus, even when the tissue 169 against which the tip assembly 18 a ofthis invention folds around the tip assembly, the bubbles formed as aresult of the activation of the tool 10 do not simply become trappedaround the tip. Instead, the fluid flow portals allow flow pathways toform. The bubbles are educted away from electrode head 155 through thesepathways. Since the bubbles are continually forced away from theelectrode head, replacement solution is able to continually flow towardsthe head so that the head is continually kept in contact with thesolution, “rewetted.” The constant rewetting of the electrode head 155facilitates a relatively constant current flow, stable arcing, betweenthe active electrode 18 a and the shaft 14.

Moreover, the convective fluid flow away from the tip assembly 18 baround the electrode head 155 prevents the bubbles that are formedadjacent the electrode head from becoming large in size. This isbecause, soon after a bubble is formed, it becomes trapped in theconvective flow and is educted away from the electrode head 155. Theconstant eduction of newly formed bubbles away from the electrode head155 prevents the bubbles that do form becoming large in size.

A second tip assembly of this invention, tip assembly 18 b, is nowdescribed by reference to FIGS. 18 and 21. Tip assembly 18 b includes anelectrode 20 b with a head 170 that is generally in the shape of aone-eighth section of the shell of a sphere. Thus, the inner surface ofthe electrode head 170 is spaced away from the adjacent surface of theinsulator sleeve 136 b. The electrode head 170 is further formed to havea small through portal 172. In some versions of the invention, head 170inscribes a section of a sphere that has a radius of 67.5 mils, portal172 has a radius of 20 mils. The electrode head is further formed withcorners 174 that both define portal 172 and the side edges of the head.Corners 174 are defined by surfaces of the head 170 that meet at 90°. Itwill also be observed that electrode head 170 has side walls 171 thatextend between the inner and outer surfaces of the electrode head. Twoof the side walls 171 extend around the outer perimeter of the electrodehead. A third side wall 171 defines portal 172.

Electrode 20 b is further formed so that a nose 173, having a squarecross section profile extends out from the distal tip of head 170. Thepurpose of nose 173 will be explained below.

Insulating sleeve 136 b of tip assembly 18 b has a head 175 with agenerally cylindrically shaped profile. The distal end of head 172 isrounded. Head 175 is further formed to have a flow cavity 176 thatextends into both the constant diameter main section and the distal endof the head. The sleeve head 175 is further formed to have a throughbore 177 that extends laterally through the head from the outer surfaceof the head into the wall with in the head that defines the base of flowcavity 176. When tip assembly 18 b is assembled, electrode 20 b isseated in sleeve 136 so that the outer surface of the electrode head170, in combination with the outer surface of the sleeve head 175 formthe outer distal end of the tip assembly. When the tip assembly 18 b isso assembled, the portal 172 formed in the electrode head 170 is inregistration with the sleeve bore 177. Thus portal 172 and sleeve bore177 form a contiguous flow pathway through which there is fluidcirculation across the inner and outer surfaces of the electrode head170.

Tip assembly 18 b of this invention is used to contour or shape thetissue to which it is applied. When the tool 10 to which the tipassembly 18 b attached is actuated, current flows between the electrodehead 170 and the exposed end of the tool sleeve 14. When the electrodehead 170 is pushed against the tissue to be ablated, nose 173 holds theside edges of the electrode head away from the adjacent surfaces ofsleeve 136 b. As a result of the heating of the solution adjacent theinner and outer surfaces of the electrode head 170, initially aconvective flow of replacement solution flows towards across theelectrode head through the contiguous flow pathway defined by electrodeportal 172 and sleeve bore 177. As part of the convective flow pattern,the heated solution also flows out of the portal.

Eventually, bubbles develop adjacent the side walls 171 of the electrodehead. These bubbles do not simply remain trapped within the tip andsurrounding tissue. Instead, these bubbles become entrained in theportion of the convective fluid flow that moves away from the tipassembly 18 b through the flow passageway. More particularly, it shouldbe understood that since flow through the flow passageway isbidirectional along the length of the passageway, these bubbles willstream out of either the electrode head portal 172 or the sleeve bore177.

The flow out of the flow passageway entrains bubbles that form aroundthe outer side walls 171 of the electrode head 170 to flow with it.Thus, the bubbles that form along the side of the electrode head 170 areeducted away from the head. This constant eduction of the bubbles servesto ensure that solution will continually flow towards the electrode head170 so as to continually keep the head wetted.

FIGS. 22 through 25 illustrate a third tip assembly 18 c. Tip assembly18 c includes an electrode 20 c with three parallel, spaced apart tines180 that are shaped to form loops. Electrode 20 c is further formed tohave small support bar 181 that extends perpendicularly across the endsof the tines that are spaced from stem 142. Once the metal forming thethird electrode 20 c is stamped out of a flat sheet of material, thetines 180 and the support bar 181 are wrapped around an anvil so thatthe support bar abuts against the distal end of the electrode stem 142.This wrapping of the metal provides the tines 180 with their loop shape.

Electrode 20 c is seated in the head end of a sleeve 136 c. The sleeve136 c is formed with a head 184 that has an outer diameter equal to theouter diameter of the adjacent shaft 14. The head is shaped so as todefine in the distal two-thirds of the head a socket space 185 forreceiving the distal end of electrode 20 c including tines 180. Morespecifically, the head 184 is provided with side walls 186 so thatapproximately 200° of the outer circumference of each loop 180 isexposed, that is, can be placed in contact with tissue. The open end ofthe sleeve head 184, in combination with the void space in center of theloops and the interstitial spaces between the tines 180, serve as aportal and sub portals between the surfaces of tines and space outsidethe tip assembly 18 c.

The sleeve head 184 is further shaped so as to project a small distancebeyond the distal end of the most forward loop 180 of the electrode 20c. Sleeve head 184 is further formed to have a post 187 that extendsforward from the wall of the sleeve that defines the rear end of socketspace 185. When the electrode 20 c is seated in the socket space 185,post 187 extends through the loops. When the tines 180 are pressedagainst the tissue, the post 187 provides mechanical support for theloops and prevents tissue from being caught in the tines.

The third electrode assembly 18 c is used to remove large masses oftissue in areas that extend perpendicular to tool shaft 14. Assembly 18c is used by positioning the electrode 20 c so that the exposed outersurfaces of the tines 180 are pressed against the tissue to be removed.When the electrosurgical tool 10 to which tip assembly 18 c is attachedis actuated, the solution surrounding the electrode tines 180 is heated.Cooler replacement solution flows towards the tines 180 from the opendistal end of the sleeve head 184. This fluid flows through the tines180 and around the sleeve post 187. The fluid then flows between thetines 180 so as to replace the fluid the heated fluid that convectivelymoves away from the tines. More particularly, as represented by arrows181 in FIG. 25, the warmed fluid tends to flow away from the electrode18 c along flow paths that parallel to the planes in which the tines 180are aligned. As represented by arrow 183, the replacement fluid flowstowards the electrode along a flow path that is generally aligned withthe center axis of the loops defined by the tines 180.

Eventually, bubbles start to rapidly form adjacent the surfaces of thetines 180. These bubbles become entrained in the convective fluid flowaway from the tines 180. Thus, these bubbles do not simply becometrapped between the tissue and the electrode where they can degrade theperformance of the tool 10. Instead, these bubbles, as part of thecirculation flow away from the electrode 20 c, stream outwardly awayfrom tip assembly 18 c.

A fourth tip assembly of this invention, tip assembly 18 d, is nowdescribed by reference to FIGS. 26-30. Tip assembly 18 d includes anelectrode 20 d with a stem 142 d shaped so that the distal end has a 90°curve. A head 190 is integrally formed with stem 142 d. The electrodehead 190 has a circular cross sectional profile. The lateral profile ofthe head 190 is that of a flattened semi-circle. The inner surface ofthe electrode head 190 is spaced away from the adjacent surface of thesleeve 136 d against which the electrode head abuts. Four windows 191,192, 193 and 194 are formed around the outer perimeter of head 190.Window 191 is formed by the void space from which the stem 142 dextends. Windows 192 and 193 are located on either side of window 191and are symmetric with respect to each other relative to that centeraxis through the head 190. Window 194 is located forward of window 191.Windows 191 is defined by straight edges. Windows 192-194 are defined bycurved edges. The radius of curvature of the edges that define window194 are greater than the radius of curvature of the edges that definewindows 192 and 193. Electrode head 190, like the other electrode headsof this invention, is shaped so that the corners around the edges of thehead and the windows 191-194 have 90° profiles.

It will also be observed that electrode head 190 has side walls 195 thatdefine the perimeters of windows 191-194. The side walls extend betweenthe inner and outer surfaces of the electrode head 190.

The sleeve 136 d of the fourth tip assembly 18 d is shaped so as to havea head 196 with a curved profile. Thus, the head has a face 198 thatlies in a plane that is parallel to the longitudinal axis of the tool 10with which tip assembly 18 d is used. The head 196 is further shaped tohave a notch 202 that extends rearward from the most distal end of thehead. Notch 202 thus provides a fluid communication path that extendsfrom the front end of sleeve head 196 to face 198.

When the electrode 20 d is seated in the sleeve 136 d, the distal end ofthe electrode stem 142 d, the curved portion, seats in the rear end ofthe space defined by notch 202. The base surface of the electrode head190 seats against the sleeve face 198. The inner surface of theelectrode head 190 is spaced above the adjacent face 198 of the sleeve136 d. When the tip assembly 20 d is so assembled, window 194 of theelectrode head 190 is in registration over the end of the notch 202 thatopens into face 198. Thus, window 194 and notch 202 collectively definea portal across the tip assembly 20 d. It should also be recognized thatsince windows 191-193 are in fluid communication with window 194 alongthe underside of the electrode head 190, windows 191-193 are likewise influid communication with notch 202. These fluid communication paths formadditional portals across the electrode head 190.

The fourth tip assembly 18 d, like the third tip assembly 18 c, is usedto remove tissue along radial lines that extend perpendicularly from thelongitudinal axis of the complementary shaft 14. The fourth tip assembly18 d, however, in comparison to the third tip assembly 18 c, removesonly relatively small amounts of tissue at any given moment. This isbecause, owing to the presence of windows 191-194, the surface area ofthe head 190 of the electrode 20 d is relatively small in size. Thus,the tip assembly 18 a is used to precisely remove relatively smallamounts of tissue.

When the tool 10 to which tip assembly 18 d is actuated, the currentflow heats the solution adjacent the electrode head 190. Consequently,convective, liquid-state fluid circulation occurs through the portals asa result of the movement of heated fluid away from electrode head 190and the flow of cooler replacement fluid towards the electrode head. Asdepicted in FIG. 30 by arrow 204 a, some of the heated fluid tends toflow away from the electrode head 190 through the top of the notch 202.As represented by arrow 204 b another portion of the heated fluid tendsto flow outwardly away from the outer surface of the electrode head 190.Some replacement fluid flow, depicted by arrow 206 a, flows to theelectrode head 190 through the lower portion of the notch 202, theportion spaced from the electrode head. Still additional replacementfluid flow, represented by arrow 206 b, flows toward the outer surfaceof the electrode head 190.

Eventually, due to the vaporization of the solution, bubbles form on theinner and outer surfaces of the electrode head 190. These bubbles becomeentrained in the convective fluid flow away from the head through notch202. Bubbles will also start to form adjacent the side walls 195 of theelectrode head 190. These bubbles likewise become entrained in theconvective fluid flow away from the tip assembly 20 d. Thus, thisembodiment of the tip assembly, like the other described embodiments,causes the bubbles to flow away from the surgical site so as to minimizethe extent to which the bubbles interfere with the surgeon's view of thesite.

The electrosurgical tool 10 of this invention is constructed so that themoving components of the switches 29 and 30 that control the actuationof the tool are built into web 108. The web 108 is constructed so thatthe act of mounting the web 108 to the nose cone 12 seals the borderbetween the web and the nose cone. Thus, the electrosurgical tool 10 ofthis invention has an on-handle mounted switch assembly for regulatingthe actuation of the tool that is both economical to install and thatdoes not form paths through which fluid can leak into the handle.

Tool 10 of this invention is also provided with an in-handleidentification resistor 105. Depending on the voltage measured acrossthis resistor 105, the complementary control console 22 configuresitself to provide the appropriate powered signal to the tool. Forexample, when the identification resistor 105 indicates that the tool 10in which the resistor is installed is designed for ear, nose and throatsurgery, the control console 22 will configure itself so as to onlyoutput a relatively small powered signal to the tool. In some versionsof the invention, the maximum power of this low power cutting modesignal may be 50 Watts. If however, the identification resistor 105indicates that the tool is used for certain orthopedic applications, thecontrol console 22 will configure itself to generate a relatively highpowered signal. For example, in some versions of this invention themaximum power of this high power cutting mode signal may be 200 Watts.In still other versions of the invention, the tool emits short bursts ofpower. When the tool is operated in this mode, it may emit up to 250Watts of power. As part of this self-configuration, the control consoleestablishes the various power settings for the tool when it is to beoperated at less than full power and also when it is to be operated inthe coagulation mode.

Moreover, in the unlikely event there is a leak of fluid into the nosecone 12, the fluid will most likely flow across conductive trace 104 aand adjacent trace 92. As represented by a resistor 107 in FIG. 9, thisfluid effectively changes the resistance across resistor 105 circuit onprinted circuit board 78. The voltage across resistor 105 is alwaysbeing measured by the voltage measuring circuit 222 internal to thecontrol console 22, even when the tool is actuated. When, due to theinsertion of resistor 107 in parallel across resistor 105, theresistance changes, the signal drops out of its normal range the controlconsole circuit 224 recognizes this voltage drop as indication thatthere is malfunction in the electrosurgical tool 10. This circuit theninhibits the generation of coagulation or ablation causing current so asto prevent persons handling the tool from being shocked. This circuitwill also actuate a warning light on the face of the control console(light not illustrated) to indicate that a fault condition has beendetected. Also, while the conductive fluid of a leak may flow across oneor both of the contact pads 96 or 102 so as to short switch 29 or 30closed, this malfunction will not result in the tool beingunintentionally actuated. Because, as described above, once the leak isdetected, the control circuit 224 will have already blocked actuation ofthe tool 10.

Still another feature of the electrosurgical tool 10 of this inventionis that the active electrode is formed out of tantalum. This metal isrelatively easy to form into place so as to ensure that the electrodehas a desired shape.

Also, the tip assemblies, 18 a, 18 b, 18 c and 18 d of this inventionare designed so that when the tool is actuated in the cutting mode, thebubbles that are generated are relatively small and flow away from thesurgical site. This regulation of bubble formation and flow serves tominimize the extent to which the bubbles both interfere with thesurgeon's view of the surgical site and the extent to which theymodulate and interrupt the current flow between the tool electrode andthe associated shaft. Both these benefits allow the surgeon to focushis/her attentions on performing a procedure with the tool 10 as opposedto dealing with the undesirable consequences of the actuation of thetool.

Moreover, when an electrosurgical tool such as the tool 10 of thisinvention is operated eschar, dead tissue, sometimes can accumulate onthe electrode head. This material can degrade the performance of thetool. However, in the tip assemblies of this invention there is theabove-discussed convective flow around the electrode head. This flowserves to remove, to clean, the tissue away from the electrode head soas reduce the effect this tissue has on the operation of the tool.

FIG. 32 depicts the distal end of a shaft 14 a of still another versionof the electrosurgical tool of this invention. Shaft 14 a is formed thesame material and performs the same general function as previouslydescribed shaft 14. Shaft 14 a, is however, larger in diameter thanshaft 14. A insulating tube 16a extends around all but the distal end ofshaft 14 a.

An insulating sleeve 136 e is fitted in the open end of shaft 14 a.Sleeve 136 e is formed to have two parallel, axially extending bores 230and 232. Electrode 20 a is fitted to sleeve 136 e so that stem 142 isseated in bore 230. Wire 126 is connected to electrode stem 142 in themanner previously described.

A lens 234 is mounted in the distal end opening of sleeve bore 232. Thelens 234 is formed from material such as fused silica glass or othermaterial that has a high degree optical transmisivity for infra-redlight, light having a wavelength between 100 nm and 1 mm. A fiber opticcable 236 is seated in bore 232 behind lens 234. Suitable cables thatcan be employed as fiber optical cable 236 are fluoride or silver halidedoped fused silica glass fiber optic cables available from OxfordElectronics of Oxford, England. In some versions of the invention, fiberoptic cable has an outer diameter of between 0.1 and 1 mm. Lens 234 ispositioned and shaped so as to focus infra-red light waves generated atthe surgical site on the distal end, the head end, of the cable 236.

Fiber optic cable 236 is extends out of the proximal end of sleeve 136 eand through sleeve 14 a. Not illustrated is protective shielding thatmay extend around the outer surface of cable 236. The fiber optic cable236 extends through the nose cone 12 to the control console 22. In someversions of the invention, the fiber optic cable 236, or a separatecomplementary fiber optic cable, is bundled in a version of cable 21 inwhich the electrical conductors that extend between the nose cone andcontrol console are bundled.

FIG. 33 illustrates how the proximal end of fiber optic cable 236extends to the control console 22 a. More specifically, internal to thecontrol console is an infra-red sensitive, photovoltaic transducer 238to which the light transmitted over fiber optic cable 26 is applied. Thesignal produced by transducer 238 is applied to tool control circuit 240as an indication of the temperature of the tissue at the surgical site.In some versions of the invention, a second lens, not illustrated, maybe positioned between the proximal end of the fiber optic cable 236 andthe transducer 238. This lens is used to either focus or diverge theinfra-red light emitted from the proximal end of the cable 236 over theinfra-red sensitive surface of the transducer 238.

In the version of the control unit 22 depicted in FIG. 33 a manually-setwiper 241 connected to tool control circuit 240 adjustably applies afraction of the voltage present across a resistor 242 to the toolcontroller. This voltage is representative of the temperature desired bythe surgeon performing the procedure.

Alternatively, one or both of the buttons 29 and 30 mounted to the nosecone 12 may be used to set the desired temperature. In these versions ofthe invention, a pulse counter and/or timer circuit is employed toconvert the signals generated by the actuation of the button 29 and/or30 into a command signal indicating the desired temperature setting isto be raised or lowered. For example, in some embodiments of thisversion of the invention, the surgeon may depress button 29 to indicatethat the temperature at the surgical site should be increased. Button 30is selectively depressed to indicate that the temperature at thesurgical site should be decreased.

When the electrosurgical tool of this invention is used to perform acapsulary shrinkage procedure, the appropriate controls are actuated onthe control console 22. Tool control circuit 240, in turn, regulates theenergization signal produced by a power supply 244 to cause anappropriate voltage to be applied to the active electrode 20 a. Theactive electrode 20 a, now in a state in which it generates thermalenergy, is applied to the tissue 169 in order to perform the capsularyshrinkage procedure. The heating of the tissue causes the quantity ofinfra-red energy emitted by the tissue to increase. A portion of thisenergy is transmitted to lens 234. The infra-red light waves received bylens 234 are focused by the lens are applied to the head end, the distalend of fiber optic cable 236. These light waves are, in turn, forwardedto transducer 238. Transducer 238 thus generates an output signal thatvaries as a function of the temperature of the tissue 169 forming thesurgical site to which the tool is applied.

The output signal produced by transducer 238 is applied to the toolcontrol circuit 240. The tool control circuit 240, based on level of thetransducer signal, performs a real time regulation of the power supply244 to ensure that tool continually heats the tissue to the desiredtemperature. If the infra-red light detected by transducer 238 rises toa level indicative of a dangerous rise in tissue temperature, toolcontroller 240 forces the attenuation of the energization signalproduced by power supply 244. Thus, the system of this inventionregulates the heating of the surgical site 12 by the tool 10 so as toprevent thermally-induced damage of the tissue forming the site.

The electrosurgical tool of this invention monitors the infra-red lightgenerated by the tissue 169 forming the surgical site. The quantity ofthis light is directly proportional to the temperature of the site.Thus, by monitoring this light, the tool directly monitors thetemperature at the surgical site. Moreover, still another feature of thetool of this invention is that the generation of this infra-red light,its collection by the lens 234 and its transmission through fiber opticcable 236 are not affected by the presence of stray electromagneticwaves that may be present due to the actuation of the tool. Thus, theelectrosurgical tool of this invention is designed so that, while theactive electrode 20 a is energized in order to heat the site 12, thetemperature of the tissue is simultaneously monitored. This is true forversions of the invention in which an AC energization signal is appliedto the electrode 20 a. One does not have to apply an energization signalin a pulsed pattern to the active electrode in order monitor sitetemperature. The tool can thus be energized continually in order to heatlarge amounts of tissue in a short amount of time so as to cause itscapsullary shrinkage.

Collectively, these features mean that the tool of this inventioncontinually applies thermal energy to a surgical site to heat the siteto a temperature at which capsulary shrinking occurs at an efficientrate and at which damage to the tissue is avoided.

It should be recognized that the foregoing description is only for thepurposes of illustration. Other embodiments of the invention may havefeatures different than what has been described. For example, not allversions of the invention may include the described on-handle switchassembly, the identification resistor, the leak detect traces 92 and 104a or one of the disclosed tip assemblies. Also, in alternative versionsof the invention, the number of switches and the function of theswitches integral with the switch assembly may vary. For example, insome versions of the invention it may be desirable to provide the switchassembly with switches that can be depressed to establish the powersetting of the electrosurgical tool. These switches may be in additionto or in substitution of the switches that regulate the on/off operationof the tool and whether or not the tool is operating in the coagulationmode or the cutting mode. It may also be desirable for some applicationsto mount a single switch to the nose cone 12.

Moreover, in other versions of the invention, multiple identificationresistors may be mounted to the printed circuit board 78. In thisconfiguration, the control circuit internal to the control console 22,would measure the voltages across these individual resistors. Based onthese voltages, different settings for the tool can be established. Forexample, it may be possible to set the control console for one from afirst set of maximum power settings when the tool is operated in thecoagulation mode and one from a second set of maximum power settingswhen the tool is operated in the cutting mode.

Alternatively, instead of providing an identification resistor, adigital memory chip may be provided internal to the nose cone 12. Thischip would store data that can be used to establish the various powersettings of the signals that are applied to the tool 10. These versionsof the invention may still contain a resistor. The resistor would servethe leak detect function which resistor 105 performs. Alternatively, thetraces on the printed wiring board can be constructed so that if fluidenters the printed wiring board, it establishes a short circuit acrossthe memory chip. In these versions of the invention, the complementarycontrol console is configured to periodically read data from this chip.If, due to the presence of the short circuit, the control console isunable to read this data, a processor internal to the control consoleinterprets this condition as indicating that there is a leak into thenose cone 12. The control console processor, in turn, takes appropriateaction to either inhibit the generation of energization signals to thetool and/or actuate the appropriate indicator to inform the surgeon ofthis fault state.

Moreover, the tip assemblies of this invention may have structuresdifferent from what has been described. Other tip assemblies, withthrough holes in the electrodes and complementary through bores in theinsulating sleeves that collectively form contiguous flow pathways maybe provided to facilitate to tissue removal in patterns not disclosed.Also, while in the disclosed version of the invention, the cornersaround the edges of the electrodes 20 are formed at 90°, that may notalways be the case. The corners between the surfaces of the electrodesmay meet at angles greater or less than 90°. The primary goal in theforming of an electrode is that shaping of its tines so that there willbe conductive fluid flow around and/or through the electrode. However,it has been observed that there are current densities that are higheraround the sharp corners of the electrodes. These higher currentdensities result in better ablation of tissue. Accordingly, it isanticipated that other preferred electrodes of this invention will beformed with heads that have sharp corners. Moreover, while in thedisclosed version of the invention the portals are oval shaped, circularor rectangular, it should be recognized that this need not always be thecase. In other versions of the invention the portals defined by theelectrode head and/or insulator sleeve may have different shapes. Forexample they may even be L-shaped or X-shaped.

Also, the dimensions of the electrodes should be understood to beexemplary and not limiting. Clearly, the windows and portals may belarger or smaller depending on the type of cutting the electrode isdesigned to perform.

Also, while in FIG. 8, the two traces 92 and 104 a that form part of theleak detect circuit are shown as running parallel to each other for alength equal to 72% of the overall length of the printed circuit board78, that need not always be in the same in each version of thisinvention. In other versions of the invention, the traces forming theleak detect circuit may run parallel to each other for shorter or longerdistances. For example, the traces may run together for a distance only.In still other versions of the invention, the leak detect traces may runtogether for a length equal to that of the printed circuit board 78 ormay even surround the complete perimeter of the printed circuit board.In these latter versions of the invention, the traces would run togetherfor a distance greater than twice the distance around the printedcircuit board.

It should similarly be recognized that the self-sealing web 108 may beinstalled in handpieces integral with surgical tools other than surgicaltools. For example, web 108, may be installed in a handpiece that ispart of a handpiece with a motor employed to actuate a cuttingaccessory. Alternatively, the web 108 may be installed in handpiece thatis part of surgical laser or surgical ultrasonic tool.

Moreover, while the described version of the electrosurgical tool 10 ofthis invention is a bipolar tool, alternative monopolar versions of thistool can be provided. A monopolar electrosurgical tool has a singleelectrode. When electrosurgery with this type of tool is performed, thepatient is externally grounded.

Furthermore, it may not be necessary to extend the fiber optic cable 236of this invention to the complementary control console 22 to which theeleoctrosurgical tool is connected. In some versions of this invention,an infra-red transducer identical or similar to transducer 238 may bemounted in the nose cone 12 of the electrosurgical tool. In theseversions of the invention, the output signal produced by the transduceris transmitted to the tool controller 222 in the control console 22 overelectrical conductors in the cable 21. An advantage of this version ofthe invention is that the need to extend the fiber optic cable to thecontrol console is eliminated. In these versions of the invention itshould be realized that the transducer may be mounted to a circuit boardinternal to the nose cone 12 that is separate and sealed from thecircuit board 78 forming the switch assembly.

Therefore, it is the object of the appended claims to cover all suchvariations and modifications that come within the spirit and scope ofthis invention.

What is claimed is:
 1. A powered surgical handpiece, said handpiececomprising: a housing, said housing have an outer surface and an openingthat is formed in the outer surface that defines a wiring space in saidhousing, the wiring space being defined by a perimeter section of theouter surface of said housing; a surgical implement that extends fromsaid housing, said surgical implement being selectively actuated basedon application of a variable control signal; a circuit board fixedlymounted in the wiring space of said housing, said circuit board havingan outwardly directed surface and a plurality of conductive tracesformed on the outwardly directed surface so as to define a contact pad;a flange fixedly disposed in the wiring space of said housing, saidflange positioned to circumferentially surround said circuit board andpositioned to be spaced inwardly of the perimeter section of the outersurface of said housing; and a web formed of elastomeric material thatis mounted to said housing, said web having: a base positioned in theopening of said housing, said base having an outer edge; a lip thatextends circumferentially around and away form the outer edge of saidbase, said lip positioned to be located between the perimeter section ofthe outer surface of said housing and said flange, said lip beingdimensioned to be compression fitted between the outer surface of saidhousing and said flange; a button formed integrally with said base sothat said button flexes relative to surrounding portions of said base,wherein said button is positioned to be located over said contact padand is constructed so that, upon depression of said button, said buttonabuts said contact pad; and a landing pad located on an undersurface ofsaid button that is directed towards said contact pad and is positioned,so that, when said button abuts said contact pad, said landing pad abutssaid contact pad, said landing pad having a layer of conductive materialthereon, so that, when said landing pad abuts said contact pad, theconductive material establishes a conductive path between saidconductive traces.
 2. The powered surgical handpiece of claim 1, whereinsaid web is further formed to have a slit in said lip that extendsinwardly from an outer surface of said web.
 3. The powered surgicalhandpiece of claim 2, wherein said web is formed so that the slitextends circumferentially around said lip.
 4. The powered surgicalhandpiece of claim 1, wherein said web is formed so that said lip has aninner surface that is directed towards said flange and the inner surfaceof said lip is formed to have a plurality of spaced apart ribs, whereinsaid ribs abut said flange.
 5. The powered surgical handpiece of claim1, wherein: said conductive traces are arranged on said circuit board toform a plurality of contact pads; and said web is formed to have aplurality of buttons, each said button being located over a separate oneof said contact pads and each said button is provided with a separatesaid landing pad.
 6. The powered surgical handpiece of claim 1, whereinsaid web is formed from silicone rubber.
 7. The powered surgicalhandpiece of claim 1, wherein said landing pad is formed from graphite.8. The powered surgical handpiece of claim 1, wherein said surgicalimplement is an electrosurgical probe having a tip from which anelectric current is discharged.
 9. The powered surgical handpiece ofclaim 1, further including: a first leak detect trace disposed on saidcircuit board; a second leak detect trace disposed on said circuitboard, said second leak detect trace having a branch that extendsparallel to said first leak detect trace; a resistor mounted to saidcircuit board, said resistor extending between said first leak detecttrace and said second leak detect trace; and a leak detect circuitexternal to said housing, said leak detect circuit being connected tosaid first leak detect trace and to said second leak detect trace, saidleak detect circuit including: a power supply for supplying a voltage tosaid leak detect traces to cause a voltage to develop across said leakdetect traces; and a voltage measuring circuit for measuring the voltageacross said leak detect traces.
 10. The powered surgical handpiece ofclaim 9, wherein: said first leak detect trace is one of said tracesthat define said contact pad and said first leak detect trace isarranged on said circuit board so as to define at least a portion of theouter perimeter of said contact pad and the branch of said second leakdetect trace is located adjacent the portion of said first leak detecttrace that defines the outer perimeter of said contact pad.
 11. Apowered surgical handpiece, said handpiecce comprising: a handle, saidhandle having an outer surface that has an opening that defines a wiringspace in said handle; an electrically actuated surgical implement thatextends from said handle; a wall integral with said handle and locatedin the wiring space, said wall being spaced inwardly from edge portionsof said outer surface of said handle that define the opening and beingformed to define a seating space within said wiring space that iscircumferentially enclosed by said wall and said wall has an outersurface; a circuit board disposed inside the seating space, said circuitboard having a contact pad that is formed by two spaced apart conductivetraces; a single-piece web formed of elastomeric material mounted tosaid handle, said web having: a circumferentially extending flange thatis disposed in the wiring space in an interstitial space between theedge portions of the outer surface of said handle and the outer surfaceof said wall, and said flange is dimensioned to be compression securedbetween the outer surface of said handle and said wall; and a base thatextends from said flange over the opening in said handle, said basebeing formed to define a button that is disposed over said contact padand said base is formed so that said button can be inwardly flexed toabut said contact pad; and a landing pad that includes a conductivelayer that is secured to a surface of said button that abuts saidcontact pad.
 12. The powered surgical handpiece of claim 11, whereinsaid web is further formed to have a slit in said flange that extendsinwardly from an outer surface of said flange.
 13. The powered surgicalhandpiece of claim 12, wherein said web is formed so that the slitextends circumferentially around said flange.
 14. The powered surgicalhandpiece of claim 11, wherein said web is formed so that said flangehas an inner surface that is directed towards said wall and the innersurface of said flange is formed to have a plurality of spaced apartribs, wherein said ribs abut said wall.
 15. The powered surgicalhandpiece of claim 11, wherein: said conductive traces are arranged onsaid circuit board to form a plurality of contact pads; and said web isformed to have a plurality of buttons, each said button being locatedover a separate one of said contact pads and each said button isprovided with a separate said landing pad.
 16. The powered surgicalhandpiece of claim 11, wherein said web is formed from silicone rubber.17. The powered surgical handpiece of claim 11, wherein said landing padis formed from graphite.
 18. The powered surgical handpiece of claim 11,wherein said surgical implement is an electrosurgical probe having a tipfrom which an electric current is discharged.
 19. The powered surgicalhandpiece of claim 11, further including: a first leak detect tracedisposed on said circuit board; a second leak detect trace disposed onsaid circuit board, said second leak detect trace having a branch thatthat extends parallel to said first leak detect trace; a resistormounted to said circuit board, said resistor extending between saidfirst leak detect trace and said second leak detect trace; and a leakdetect circuit external to said housing, said leak detect circuit beingconnected to said first leak detect trace and to said second leak detecttrace, said leak detect circuit including: a power supply for supplyinga voltage to said leak detect traces to cause a voltage to developacross said leak detect traces; and a voltage measuring circuit formeasuring the voltage across said leak detect traces.
 20. The poweredsurgical handpiece of claim 19, wherein: said first leak detect trace isone of said traces that define said contact pad and said first leakdetect trace is arranged on said circuit board so as to define at leasta portion of the outer perimeter of said contact pad and the branch ofsaid second leak detect trace is located adjacent the portion of saidfirst leak detect trace that defines the outer perimeter of said contactpad.
 21. A powered surgical handpiece, said handpiece comprising: ahousing, said housing have an outer surface and an opening that isformed in the outer surface that defines a wiring space in said housing,the wiring space being defined by a perimeter section of the outersurface of said housing; a surgical implement that extends from saidhousing, said surgical implement being selectively actuated based onapplication of a variable control signal; a circuit board fixedlymounted in the wiring space of said housing, said circuit board havingan outwardly directed surface and a plurality of conductive tracesformed on the outwardly directed surface so as to define a contact pad;a flange fixedly positioned in the wiring space of said housing, saidflange positioned to circumferentially surround said circuit board andpositioned to be spaced inwardly of the perimeter section of the outersurface of said housing; and a web formed of elastomeric material thatis mounted to said housing, said web having: a base positioned in theopening of said housing, said web having an outer edge; a lip thatextends circumferentially around and away form the outer edge of saidbase, said lip formed to have a slit that extends inwardly from an outersurface of said web and that extends circumferentially around said baseand an inner surface that is formed to have a plurality of spaced-apartribs and said lip is positioned to be located between the perimetersection of the outer surface of said housing and said flange and isdimensioned to be compression fitted between the outer surface of saidhousing and said flange so that said ribs abut said flange; a buttonformed integrally with said base so that said button flexes relative tosurrounding portions of said base, wherein said button is positioned tobe located over said contact pad and is constructed so that, upondepression of said button, said button abuts said contact pad; and alanding pad that includes a layer of conductive material attached to asurface of said button that is directed towards said contact pad, sothat when said button abuts said contact pad, said landing pad abutssaid conductive traces that form said contact pad and the conductivematerial establishes a conductive path between said conductive traces.22. The powered surgical handpiece of claim 21, wherein: said conductivetraces are arranged on said circuit board to form a plurality of contactpads; and said web is formed to have a plurality of buttons, each saidbutton being located over a separate one of said contact pads and eachsaid button is provided with a separate said landing pad.
 23. Thepowered surgical handpiece of claim 21, wherein said web is formed fromsilicone rubber.
 24. The powered surgical handpiece of claim 21, whereinsaid landing pad is formed from graphite.
 25. The powered surgicalhandpiece of claim 21, wherein said surgical implement is anelectrosurgical probe having a tip from which an electric current isdischarged.
 26. The powered surgical handpiece of claim 21, furtherincluding: a first leak detect trace disposed on said circuit board; asecond leak detect trace disposed on said circuit board, said secondleak detect circuit trace having a branch that extends parallel to saidfirst leak detect trace; a resistor mounted to said circuit board, saidresistor extending between said first leak detect trace and said secondleak detect trace; and a leak detect circuit external to said housing,said leak detect circuit being connected to said first leak detect traceand to said second leak detect trace, said leak detect circuitincluding: a power supply for supplying a voltage to said leak detecttraces to cause a voltage to develop across said leak detect traces; anda voltage measuring circuit for measuring the voltage across said leakdetect traces.
 27. The powered surgical handpiece of claim 25, wherein:said first leak detect trace is one of said traces that define saidcontact pad and said first leak detect trace is arranged on said circuitboard so as to define at least a portion of the outer perimeter of saidcontact pad and the branch of said second leak detect trace is locatedadjacent the portion of said first leak detect trace that defines theouter perimeter of said contact pad.